A duodenal diverticulum is categorized as periampullary, especially when it arises within 2-3 cm of the ampulla of Vater [7]. Periampullary diverticulum (PAD) causes ampullary dysfunction either due to functional dysfunction, persistent inflammation leading to fibrosis, or mechanical compression of the distal common bile duct and ampulla [7-10]. Diagnosis of Lemmel syndrome is made by imaging. The cholestatic pattern of serum LFTs (elevated alkaline phosphatase (ALP), direct bilirubin, and/or transaminase) can be supportive, but it is not uncommon in normal serum chemistry despite radiographic evidence of Lemmel syndrome, such as depicted in our case where ALT and AST were elevated but ALP and bilirubin were within normal limits [1,11]. There is no standardized approach for imaging; ultrasonography is usually used as the first choice. Interestingly, diagnosis of Lemmel syndrome has never been made only with ultrasound; an additional mode of imaging is usually required. A CT scan of the abdomen and pelvis with intravenous contrast is sensitive and commonly performed, often being sufficient for diagnosis. However, the lack of specificity of CT scans is often deceptive as pancreatic neoplasms or pseudocysts [11,12,7]. Therefore, more specific modalities such as magnetic resonance cholangiopancreatography (MRCP) or endoscopic ultrasound are often necessary. ERCP comes in a little more handy as it offers both diagnostic and therapeutic benefits; however, diagnosis can be made only 50% of the time with the endoscopy, hence imaging such as MRCP still needs to be performed [1,11,13].

There is no standardized treatment approach, and clinical decisions should be tailored to each individual patient, and the most definitive treatment is diverticulectomy [13]. However, not all patients warranted surgical intervention. Asymptomatic or minimally symptomatic patients can be managed conservatively with a high-fiber diet as an option [1,2,7,14]. Patients with obstructive pancreaticobiliary complications warrant interventional approaches such as ERCP with sphincterotomy or stenting, diverticulectomy with or without antibiotic coverage (antibiotic use is necessary in the setting of cholangitis, sepsis, and such as in high-risk patients) [1,9]. However, many cases have been reported as unique approaches varying upon a subjective basis, such as diverticular lavage as a bridge for diverticulectomy for symptomatic relief, and extracorporeal shock wave lithotripsy [14,15]. Altered anatomy in such uncommon cases can make it challenging to perform usual procedures. In our case, we initially attempted an ERCP, but after a failed attempt, interventional radiology performed a percutaneous cholecystostomy to prevent sepsis from choledocholithiasis. Eventually, we conducted an ERCP with sphincterotomy for the drainage of sludge and stones and to relieve compression.

In our case, while CBD (common bile duct) stones are likely contributing to abdominal pain, we cannot entirely dismiss the possibility that compression from a periampullary diverticulum (PAD) is playing a role. The compression could cause the pain directly or indirectly, leading to cholestasis, which may have facilitated stone formation. Additionally, it was unexpected that the patient's alkaline phosphatase (ALP) and bilirubin levels remained normal in the context of choledocholithiasis, despite elevated ALT and AST levels. However, the normalization of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels following sphincterotomy highlights the combined influence of both the diverticulum and the stone on this clinical presentation. This suggests that the interaction between these two factors, diverticular compression and the presence of stones, was likely responsible for the symptoms and abnormal liver function tests observed before the procedure.